Extended Data Fig. 5: Horizontal temperature difference versus latitude.

(a-w) CMIP simulations. (a) Results of a model from Group A (blue curve in FC. 2C). (b) Results of a model from B (the NASA GISS model; green curve in Fig. 2C). (x) ERA results. In each panel, the red solid line is directly diagnosed temperature difference \({{\Delta }}T\), and the black dashed line is vapor buoyancy-induced temperature difference \({{\Delta }}T_{{{{\mathrm{vb}}}}}\), which is calculated using Eq. (1). We divide the models into two groups: one properly incorporates VB (Group A), and the other does not (Group B). Group B include models in (b) NASA GISS-E2-1-G, (g) CAS-ESM2-0, (i) CNRM-CM6-1, (m) FGOALS-g3, (p) IITM-ESM, and (q) IPSL-CM6A-LR, in which temperature is horizontally uniform, and \({{\Delta }}T_{{{{\mathrm{vb}}}}}\) cannot explain \({{\Delta }}T\). Quantitatively, we identify Group B as those models with \({{\Delta }}T\) < 0.1 K at −10° latitude. All other models belong to Group A. This figure is created using boreal summer data.